The present invention relates to a composition suitable for use as a curing agent and adhesion promoter in a silicone weatherstrip coating. In particular, it relates to an amine functional silane modified epoxy resin composition used in combination with a OH-terminated diorganosiloxane coating to give a weatherstrip coating having good freeze-release properties, improved abrasion resistance and good adhesion to EPDM based weatherstrip.
A wide variety of OH-terminated diorganosiloxane coatings having freeze-release properties are known and are readily available. Most of the coatings are used to treat paper and other porous substrates such that the adhesion of the coating to the substrate is primarily based on physical anchorage. On non-porous substrates such as plastics and rubber surfaces, adhesion of these coatings is poor. Furthermore, the coatings have little resistance to removal by abrasion.
Because of the aforementioned problems associated with adhering coatings containing OH-terminated diorganosiloxane to non-porous substrates, it has been necessary to apply various primers to the substrate before applying the OH-terminated diorganosiloxane coating.
U.S. Pat. No. 4,233,428 of Isao Endo, issued Nov. 11, 1980 and assigned to General Electric Company, teaches a primer composition comprising an epoxy resin, an amine functional silane, an aminoxy functional silane or siloxane, a mercapto functional silane, and an organic solvent. Such composition is used as a primer for aminoxy curing room temperature vulcanizable silicone rubbers. The overall process of adhering curable silicone rubber compositions requires two separate steps.
U.S. Pat. No. 4,311,737 of Mitsuo Ishizaka issued Jan. 19, 1982 and assigned to General Electric company, teaches a silicone release coating comprising a polysiloxane having glycydoxy or epoxycyclohexyl groups and an amine functional silane or siloxane. These compositions provide good water repellant properties and adhesion to plastics, paper and rubber.
U.S. Pat. No. 4,252,933 of Heiji Sumida, issued Feb. 24, 1981 and assigned to General Electric Company, teaches a composition comprising a hydroxy-terminated polysiloxane, a polysiloxane having epoxy functional groups, an amine functional silane or siloxane, a hydride-containing polysiloxane and a metal salt of carboxylic acid. Such compositions are suitable for use on rubber surfaces to give non-sticking, water repellant properties and good adhesion.
There is no teaching of a one step application for an amine functional silane modified epoxy resin composition in combination with a OH-terminated diorganosiloxane composition for use as a weatherstrip coating. It has been discovered that this novel weatherstrip coating has improved abrasion resistant and freeze-release properties over those of Sumida due to the addition of an amine functional silane modified epoxy resin composition.